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Fixes index out of bounds crash in hello-todo-terminal sample #605

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Merged
merged 1 commit into from
Dec 10, 2021
Merged

Fixes index out of bounds crash in hello-todo-terminal sample #605

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27 changes: 15 additions & 12 deletions ...erminal/todo-terminal-app/src/main/java/com/squareup/sample/hellotodo/EditTextWorkflow.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ class EditTextWorkflow : StatefulWorkflow<EditTextProps, EditTextState, String,
override fun initialState(
props: EditTextProps,
snapshot: Snapshot?
) = EditTextState(props.text.length)
) = EditTextState(cursorPosition = props.text.length)

override fun onPropsChanged(
old: EditTextProps,
Expand All @@ -40,7 +40,7 @@ class EditTextWorkflow : StatefulWorkflow<EditTextProps, EditTextState, String,
): EditTextState {
return if (old.text != new.text) {
// Clamp the cursor position to the text length.
state.copy(cursorPosition = state.cursorPosition.coerceIn(0..new.text.length))
state.copy(cursorPosition = state.cursorPosition.coerceIn(new.text))
} else state
}

Expand Down Expand Up @@ -68,18 +68,19 @@ class EditTextWorkflow : StatefulWorkflow<EditTextProps, EditTextState, String,
) = action {
when (key.keyType) {
Character -> {
state = moveCursor(props, state, 1)
props.text.insertCharAt(state.cursorPosition, key.character!!)
val newText = props.text.insertCharAt(state.cursorPosition, key.character!!)
setOutput(newText)
state = moveCursor(newText, state, 1)
}

Backspace -> {
if (props.text.isNotEmpty()) {
state = moveCursor(props, state, -1)
props.text.removeRange(state.cursorPosition - 1, state.cursorPosition)
if (props.text.isNotEmpty() && state.cursorPosition > 0) {
val newText = props.text.removeRange(state.cursorPosition - 1, state.cursorPosition)
setOutput(newText)
state = moveCursor(newText, state, -1)
}
}
ArrowLeft -> state = moveCursor(props, state, -1)
ArrowRight -> state = moveCursor(props, state, 1)
ArrowLeft -> state = moveCursor(props.text, state, -1)
ArrowRight -> state = moveCursor(props.text, state, 1)
else -> {
// Nothing to do.
}
Expand All @@ -88,13 +89,15 @@ class EditTextWorkflow : StatefulWorkflow<EditTextProps, EditTextState, String,
}

private fun moveCursor(
props: EditTextProps,
text: String,
state: EditTextState,
delta: Int
): EditTextState =
state.copy(cursorPosition = (state.cursorPosition + delta).coerceIn(0..props.text.length + 1))
state.copy(cursorPosition = (state.cursorPosition + delta).coerceIn(text))

private fun String.insertCharAt(
index: Int,
char: Char
): String = substring(0, index) + char + substring(index, length)

private fun Int.coerceIn(text: String): Int = coerceIn(0..text.length)